In a well known design for a chair with a reclining backrest, an armrest consists of at least two parts, a vertical portion and a horizontal portion. The vertical portion is attached to the seat portion of the chair at its lower end and to the front of the horizontal portion at its upper end. The horizontal portion is attached to the vertical portion at its front end and to the backrest of the chair at its back end. At the intersection of the vertical portion and the horizontal portion, the armrest can be adjusted in accordance with the inclination of the backrest portion of the chair by a series of slots on the underside of the horizontal portion of the armrest which mate with a protuberance on the end of a support member. A design such as this is used primarily in folding or patio chairs and is unsuitable for more elegant chair designs.
In another design for a chair with a reclinable backrest, the vertical portion of the armrest is fixedly attached to the chair seat at its lower end. In this design, a gap develops between the back of the horizontal portion of the armrest and the backrest of the chair when the backrest of the chair is reclined. If the horizontal portion of the armrest is of sufficient length to prevent such a gap, then the horizontal portion must necessarily protrude from the back of the chair when the back of the chair is in its upright position.
In a further prior art design, the horizontal portion of the armrest is fixedly attached to the backrest of the chair at its back end. The disadvantage to this design is that the armrest is raised at its front end upon the reclining of the backrest of the chair.